1032 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 42, NO. 4, APRIL 2014 Prototype of a Diagnostic Calorimeter for BATMAN: Design and Preliminary Measurements Michela De Muri, Mauro Pavei, Andrea Rizzolo, Federica Bonomo, Peter Franzen, Rudolf Riedl, Benjamin Ruf, Loic Schiesko, Matteo Valente, Vannino Cervaro, Daniele Fasolo, Luca Franchin, Marco Tollin, Roberto Pasqualotto, and Gianluigi Serianni Abstract—The ITER neutral beam injection system is being designed to provide 33 MW of heating from two injectors, with an upgrade to 50 MW possible with a third injector; such heating power will be provided by accelerating negative ions to high energies, 1 MeV, and neutralizing them. These neutrals are then injected into the tokamak where they impart their energy by collisions. To study and optimize negative ion production, the SPIDER prototype is under construction in Padova, Italy, whose beam has an energy of 100 keV and a current of 48 A. The instrumented calorimeter Short-Time Retractable Instrumented Kalorimeter Experiment (STRIKE) has been designed with the main purpose of characterizing the SPIDER negative ion beam in terms of beam uniformity and beam divergence during short operations (several seconds). STRIKE is made of 16 1-D carbon fiber composite (CFC) tiles, intercepting the whole beam and observed from the rear side by infrared (IR) cameras. With two identical samples of the CFC material and the IR camera under assessment, a reduced version of the entire calorimeter has been built, with the purpose of characterizing its diagnostic properties. This mini-STRIKE was used in the BATMAN experiment at Max Planck Institut für Plasmaphysik (Garching, Germany). As the beamlet divergence in BATMAN is large, the beamlets overlap each other in the measurement position; therefore, the mini-STRIKE for BATMAN includes a copper mask, facing the beam and featuring eight apertures. Thus, eight different portions of the beam can be simultaneously sampled, with minimal overlapping of the power coming from adjacent apertures. The copper mask was actively cooled, and calorimetry was carried out. The temperature in the center of the mask and some positions along the CFC tiles was also measured. In this paper, the design of the system is presented. The calorimetry system is presented in detail as well as the procedure adopted for calorimetrical data analysis. The results of calorimetry are presented together with preliminary correlations with the BATMAN beam features. Index Terms— Beam diagnostics, calorimetry, diagnostic calorimeter, negative ion beam. Manuscript received July 30, 2013; revised December 13, 2013; accepted February 8, 2014. Date of publication March 27, 2014; date of current version April 8, 2014. This work was supported by F4E. M. De Muri, M. Pavei, A. Rizzolo, F. Bonomo, M. Valente, V. Cervaro, D. Fasolo, L. Franchin, M. Tollin, R. Pasqualotto, and G. Serianni are with Consorzio RFX, Euratom-ENEA Association, Padova 35127, Italy (e-mail: michela.demuri@igi.cnr.it; mauro.pavei@igi.cnr.it; andrea.rizzolo@igi.cnr.it; federica.bonomo@igi.cnr.it; matteo.valente@igi.cnr.it; vannino.cervaro@igi. cnr.it; daniele.fasolo@igi.cnr.it; luca.franchin@igi.cnr.it; marco.tollin@igi. cnr.it; roberto.pasqualotto@igi.cnr.it; gianluigi.serianni@igi.cnr.it). P. Franzen, R. Riedl, B. Ruf, and L. Schiesko are with Max-Planck- Institut für Plasmaphysik, München D-85748, Germany (e-mail: peter. franzen@ipp.mpg.de; rudolf.riedl@ipp.mpg.de; benjamin.ruf@ipp.mpg.de; loic.schiesko@ipp.mpg.de). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TPS.2014.2306438 I. I NTRODUCTION T HE SCOPE of the SPIDER device (100-kV acceleration voltage, 48-A extracted current) [1] is to optimize the source of the ITER heating neutral beams. The requirement of the beam uniformity higher than 90% is particularly important. This parameter will be measured by the diagnostic calorimeter Short-Time Retractable Instrumented Kalorimeter Experiment (STRIKE), whose main components are 16 carbon fiber composite tiles [2]. The heat conduction inside the tiles is essentially unidirectional, so that the thermal pattern due to the beam power deposited on the front of the tile is transferred with minimal distortion onto the rear side, where it is measured by a thermal camera. Several prototype tiles are being studied and compared to choose the most suitable for the final diagnostic [3]. Among such tests, a small-scale though complete diagnostic calorime- ter, mini-STRIKE, has been developed and installed by means of such prototypes, with the aim of studying the properties of the BATMAN beam at Max Planck Institut für Plasmaphysik (Garching bei München, Germany) [4]. This paper describes in detail the design of mini-STRIKE and its functional tests and is particularly concerned with the calorimetry of the copper mask located in front of the tiles. II. DESIGN To investigate the vertical BATMAN beam homogeneity, the final design of the mini-STRIKE used two tiles simultaneously exposed to the beam [5]. The arrangement included a mask with eight apertures, just in front of the prototypes at a distance of 10 mm, to reproduce a SPIDER-like geometry [5] since the system had to be installed at 1 m from the source, where beamlets are almost completely overlapping. The actively cooled copper mask is 10-mm thick. A plate is required at the bottom to protect the tiles against particles coming from a titanium pump located just below it. Several position adjustments are present. The rear side of the tiles is observed by a thermal camera (8–12 μm) mounted on a viewport of the large vacuum flange, through a zinc selenide window. A second porthole is dedicated to the extraction of thermocouple signals and cooling tubes. Three thermocouples are mounted at the rear side of the tile, to calibrate the thermal camera. One further thermocouple is installed at the rear side of the mask, in the proximity of the beam power density peak, to monitor the copper temperature. N-type thermocouples have been used. 0093-3813 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.